Process for color development of photographic materials



Patented Dec. 1, 1942 UNITED STATES I PROCESS FOR COLOR DEVELOPMENTVOF H rno'roeaarmo MATERIALS 7 Wilhelm Schneider, Dessau in Anhalt, and Gustav Wilmanns, Woli'en, Kreis Bitterfeld, Ger-H many,,assignors to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application February 28, 1940, Se-

rial No; 321,209. In Germany February 23, 1939 3 Claims.

This invention relates to color photography and more particularly to color development of photographic materials.

It has been proposed to use in the production of photographic color pictures as developing agent for color development of silver halide emulsions, developers as such phenylene diamine, aminophenol, dihydroxybenzene.

Phenylene diamines, amino phenols and dihydroxybenzenes are frequently used as developing agents in known processes for color, development of silver halide emulsion layers. These developing agents together with suitable color formers, for instance phenols, anilines and compounds with reactive methylene and methyl groups, form quinone imineand azomethine dyes, depending on the color formers used, by means of the exposed silver salt. After dissolving the silver formed during the reaction, a pure dyestuff image is obtained. The color formers or the developing agents or both may be added This invention is based on the observation, that color images of excellent brilliancy and not too contrasty are obtained, when heterocyclic nitrogen-containing bases are added to the color-developer.

Suitable heterocyclic bases are for instance piperldine, piperazine, lysidine.

Especially effective developers are obtained according to the new process.

reversal-developers for black. and white development, but from the eflect of these developers nobody could predict the results obtained by the new process.

The process is applicable to color development with developers containing the color formers in the solution and to color development of silver halide emulsions containing the color formers in the emulsion layer itself. When using silver halide emulsion layers with color formers contained therein, color formers fast to diffusion according to the following U. S. Patents are especially suitable: 2,178,612, 2,179,- 234, 2,179,238, and 2,179,239, issued on November 7, 1939; and 2,186,849, issued on January 9, 1940.

In the following examples such developers are described:

Example I Diethyl-p-phenylene-diamine chlorine hyto the developing solution or incorporated into E32; 3: the emulsion layers' Potassium bromide "ff do 2 5 Images of suflicient color density and bril- Potassium carbonatg 1 liancy are obtained in the process of modem Piperidine "1 o 9 color development, after correct developing to 'y-inflnity. They show, however, atoo contrasty Example II gradation. For a medium gradation with har-, water "liter" 1 monious tone values required in most cases, developmem to ww is not desirable git; I.Zffffffiiffififi-fffiffiim il 2.5 ever, in such a case the sensitivity of the ma- Potassium carbonate 7' terial is only partly utilised and there is the sodium m 0 5 disadvantage, that the colors become very thin Potassium bromide 5 and pervious to a large amount of white light Pyrrondine 5 during the copying process, which results in blackish com Time for development 10 minutes.

gt is an object of the present invention to pro- Example 11 vi e a process for color development of photographic materials i tl i l hen lene diamin chlorin l i 1 A iIfnurther object resides in the provision of l e Z y e i 2 5 an proved color-developer containing novel components for color development of a hargggii fggf i "38"" monious, not too contrasty gradation. Potassium 'g"'-"" 5 Still further objects will become apparent from houne 4 the detailed specification following hereinafter. p

Time for developmentlO minutes.

What we claim is: r a

1. A color forming photographic developer comprising a primary aromatic amino developing agent, a compound which couples with the oxidation product of the developing agent on photographic development to produce a dyestufi and a nitrogen-containing heterocyclic base selected from the group consisting o1 piperldine,

It was already known to add dlamlnes to pyrrolidine, morpholine, piperazine and lysidine.

Water liter 1 I 2. A color forming photographic developer consisting of a p-phenylene diamine salt as a primary aromatic amino developing agent, a compound which couples with the oxidation product of the developing agent on photographic development to produce a dyestufi and a nitrogencontaining heterocyclic base, selected from the group consisting of piperidine, pyrrolidine, morpholine, piperazlne and lysidine.

3. A color forming photographic developer 10 

